Every morning, clinics across Canada hand blood tubes and urine cups to couriers headed for referral labs. The bag those samples travel in is easy to overlook — until a shipment gets refused, delayed, or flagged during an audit. This guide covers UN3373 classification, how IATA Packing Instruction 650 shapes specimen transport bags, and what Transport Canada expects under the TDGR, so your front desk and lab staff can ship with confidence.
What does UN3373 classification mean for your lab?
UN3373 is the proper shipping name assigned to Biological Substances, Category B — clinical samples that are unlikely to cause disease but still need controlled handling. Routine blood draws, urine cultures, nasal swabs and biopsy material typically fall here. The classification originates in the UN Model Regulations and is adopted by IATA's DGR and Canada's TDGR alike.
Category A is a different world. If a sample may contain a pathogen capable of causing permanent disability or life-threatening disease, it ships as UN 2814 or UN 2900 under far stricter rules. Misclassifying a Category A specimen as Category B is a common compliance failure in diagnostic labs — and the kind of error that surfaces in Transport Canada inspections.
What does IATA 650 require for specimen transport bags?
When specimens fly, IATA's Dangerous Goods Regulations take over, and Packing Instruction 650 is the section most clinics will ever need. PI 650 requires a triple packaging system:
- A leak-proof primary receptacle — the tube or vial holding the sample
- Leak-proof secondary packaging around the primary, with enough absorbent material to soak up the entire contents if the tube breaks
- A rigid outer packaging that survives normal transport conditions and carries the UN 3373 marking
The layers work as a system, not a stack of bags. Absorbent material sits between primary and secondary layers, and the outer package handles drops, stacking and vibration. In many clinic workflows the specimen transport bag doubles as the secondary layer: the tube goes in with its absorbent wrap, the bag seals shut, and paperwork rides in the outer pouch.
What does the 95 kPa leak test prove?
That 95 kPa figure on 95 kPa specimen bags comes straight from the UN packaging standards behind PI 650. Primary receptacles for infectious substances must withstand an internal pressure differential of at least 95 kPa without leaking — roughly the pressure shift a sample experiences during air transport at altitude. Packaging that passes earns its certification; packaging that doesn't is a liability in your courier's hands.
CliniEco's medical specimen transport bags are rated to that 95 kPa standard, so the secondary layer holds up under real shipping conditions. Compared to generic zip-close bags sold as "sample bags," a 95 kPa rated bag removes a variable from your audit trail before the courier arrives.
| Requirement | 95 kPa specimen bag | Generic zip-close sample bag |
|---|---|---|
| Pressure rating | Tested to a pressure differential of at least 95 kPa without leaking | No pressure rating and no test basis |
| Role in the package | Leak-proof secondary layer in a three-layer system | Not a recognised packaging layer |
| Absorbent material | Paired with a pad sized to absorb the entire contents of the primary receptacle | Usually absent; the absorbent has to be added and sized separately |
| Requisition handling | Separate document pocket, so the requisition never travels inside the secondary layer | Paperwork shares the same space as the sample |
| Rigid outer packaging | Still required — the bag on its own is not the outer layer | Still required, and the bag cannot substitute for it |
| Audit trail | Removes a variable from your audit trail before the courier arrives | Removes nothing an inspector can check |
Marking, Labelling and the Biohazard Symbol
A compliant shipment carries more than a biohazard symbol. Under IATA 650 and TDGR, Category B packages need the UN 3373 marking on the outer packaging, the proper shipping name "Biological Substances, Category B" nearby, and the shipper's name and address. The biohazard label on the specimen bag itself tells lab staff and couriers to handle the contents carefully before sealing.
Health Canada's biosafety guidance and the Public Health Agency of Canada's laboratory standards reinforce the same idea: clear labelling prevents the exposures that happen when a bag is mistaken for routine mail. PHAC's pathogen safety data sheets list transport requirements for specific organisms, and Toronto General's lab protocols follow the same IATA framework. The primary receptacle side is covered by UN 3373 and IATA packing instruction 650; CSA Z316.6 applies to sharps containers, not to specimen bags.
What does Transport Canada require for road transport?
Air isn't the only route. When specimens move by road within Canada, the Transportation of Dangerous Goods Regulations — administered by Transport Canada — govern the shipment. TDGR aligns closely with the UN system, so a package built for IATA 650 generally satisfies road transport too, but the paperwork differs. TDGR requires shipping documents that describe the goods, and consignors must keep copies on file for the period the regulations specify and produce them during an inspection.
Record keeping is where many clinics slip. A shipping log with the date, contents, courier, tracking number and staff initials sounds administrative, but it's the first thing an auditor asks for. Labs accredited to ISO 15189, the international standard for lab quality, already treat this as routine — and the documentation habits hold whether you buy from McKesson, Medline or a specialty supplier like CliniEco.
Build a Simple Specimen Transport Workflow
If you're setting this up from scratch, a practical checklist looks like this:
- Stock 95 kPa specimen transport bags at every draw station
- Pair each bag with an absorbent pad sized for the largest tube it will carry
- Apply the UN 3373 marking and Category B label to the outer package
- Log every outbound shipment before the courier leaves
- Review classification training with lab staff once a year
The same mindset covers the rest of the clinic's consumables. CliniEco's leak-proof red biohazard waste bags handle regulated waste that stays on site, and its sterile 12-ply gauze sponges keep draw stations stocked between shipments. Standardizing the transport lane — from the 95 kPa bags to the labelling and the logbook — turns a compliance checklist from a scramble into a routine.
None of this requires a dedicated compliance officer. Specimen transport bags that meet UN3373 packaging requirements, staff who can tell Category A from Category B, and a shipping log that never gets skipped will carry a small clinic through most audits. Standardize on IATA 650 compliant bags and the paperwork gets simpler — one less thing to explain to an inspector, and one more layer of protection for the people handling your samples.
Related Reading
Explore more guides in this category:
- PHA Specimen Bags: Biodegradable Lab Transport Options
- Specimen Collection: Choosing the Right Leak-Proof Sample Cups for Canadian Labs
- Specimen Bag Types: Leak-Proof Standards for Canadian Labs
Where can Canadian labs and clinics buy 95 kPa specimen transport bags?
In Canada the workable answer is a supplier who stocks the bag domestically and can say which primary receptacle it has been paired with — not a US packaging broker. UN3373 is the same entry on both sides of the border, but the courier lane, the lead time and the paperwork expectations are Canadian questions. The packaging rules themselves come from the UN Model Regulations, which IATA Packing Instruction 650 and the Canadian Transportation of Dangerous Goods Regulations both adopt, so a bag that meets the requirement here meets it there; what changes is how quickly you can restock a clinic that runs out mid-week.
The configuration that gets ordered most often is a 6 x 9 inch UN3373 bag, 95 kPa, 100 per pack, with the document pocket separated from the sample compartment so the requisition never travels inside the secondary layer. Two specifications decide whether a bag is usable in daily practice: absorbent material sized to absorb the entire contents of the primary receptacle, and a rigid outer package, because the bag on its own is not the outer layer. Sites running several collection points can request a bulk quote and keep the same configuration on every shelf. Sites that also run an in-house sterilizer can add the BI 5-pack trial for the monitoring side of that workflow.
The Canadian buying point: UN3373 and Packing Instruction 650 are the same requirements on both sides of the border, so what actually differs between suppliers is stock position and how the item is specified. A clinic that runs out of bags mid-week cannot wait on a cross-border shipment, and the detail the person packing the shipment reads first is the pressure rating printed on the bag itself rather than a claim on a catalogue page. CliniEco stocks the 6 x 9 inch UN3373 bag, 95 kPa, 100 per pack, with the rating on the bag and a separate document pocket for the requisition.
Related Reading
- Laboratory consumables for Canadian collection sites
- Choosing 95 kPa specimen bags: sizes, absorbent pads and what matters
- Specimen bag types and leak-proof standards
- Biohazard specimen transport bags: Canadian regulatory requirements
- UN3373 specimen transport bags, 100-pack
- diagnostic & research lab supplies
- free Ontario sterilization compliance log
Frequently Asked Questions
What does UN3373 mean on a specimen transport bag?
UN3373 is the proper shipping name for Biological Substances, Category B — clinical samples that are unlikely to cause disease but still need controlled handling, such as routine blood draws, urine cultures, nasal swabs, and biopsy material. The classification comes from the UN Model Regulations and is adopted by both IATA's DGR and Canada's Transportation of Dangerous Goods Regulations.
What is the 95 kPa leak test on specimen bags?
The 95 kPa figure comes from UN packaging standards behind IATA Packing Instruction 650. Primary receptacles for infectious substances must withstand an internal pressure differential of at least 95 kPa without leaking — roughly the pressure a sample tube can see during air transport. A bag marked 95 kPa has been tested to that requirement, which is why labs and couriers look for the marking.
What is the triple packaging rule for shipping specimens?
IATA Packing Instruction 650 requires three layers: a leak-proof primary receptacle (the tube or vial), leak-proof secondary packaging with enough absorbent material to soak up the entire contents if the tube breaks, and a rigid outer packaging that carries the UN 3373 marking. In clinic workflows, the specimen bag often doubles as the secondary layer with the absorbent wrap around the tube.
What is the difference between Category A and Category B specimens?
Category B (UN3373) covers samples unlikely to cause disease in healthy people. Category A (UN 2814 or UN 2900) applies when a sample may contain a pathogen capable of causing permanent disability or life-threatening disease. Misclassifying a Category A specimen as Category B is a common compliance failure — and the kind of error surfaced in Transport Canada inspections.
Do specimen transport bags need to be rigid?
The primary and secondary layers must be leak-proof, and the outer packaging must be rigid enough to survive normal transport. A 95 kPa specimen transport bags with a rigid outer pouch satisfies the outer packaging role for most clinic-to-lab shipments. Check your courier's requirements and Transport Canada guidance for the exact configuration.
Can I buy 95 kPa specimen transport bags in Canada?
Yes. CliniEco Medical stocks UN3373 6 x 9 inch specimen transport bags, 95 kPa, in packs of 100, with the pressure rating printed on the bag and a separate document pocket for the requisition. The bag serves as the secondary layer of a three-layer package; a rigid outer container and absorbent material sized to the primary receptacle are still required, and both travel with the same order.
CliniEco Medical supplies 95 kPa specimen transport bags designed for clinic-to-lab workflows. Check the CliniEco website for specifications and bulk pricing.
Also read: learn medical waste bag film standards in our pillar article on dart impact and seal integrity.
Last updated: September 15, 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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